In the 1970s, images from the NASA Mariner 9 orbiter revealed water-sculpted surfaces on Mars. This settled the once-controversial question of whether water ever rippled over the red planet.

Mars may once have hosted a warm, ocean-bearing environment, according to new data collected by a rover that explored an area believed to be an ancient shoreline. The evidence points to buried “beach” deposits,

Scientists have used orbiters and rovers to find dried streams, lakes, and gullies on Mars that hint at its watery past, but their cavalry of robots has struggled to prove the Red Planet ever had an actual ocean.